Surprising news about Lionel Shriver, isn't it? The novelist has filled her new book with enthusiastic references to the Fundu Lagoon holiday resort in Zanzibar, after enjoying a free trip there.

Shriver has explained that this was not a product-placement deal; nevertheless, many people will be scandalised to imagine a buyable writer. I myself was shocked. It took me three cups of rich, satisfying Café Hag to get over it.

We believe that true artists should give no thought to material gain, their creative spirit unsullied by any concern for income or expenditure. That's terrific, unless you have to live with one. If not, we love the unworldly artist. This is why we must extend a hug to Henry Dagg.

Dagg, a sculptor, was paid £27,000 to create three "naturally powered sound sculptures" for the garden of the English Folk Dance and Song Society. That was in 2006. He said it would take six months. Four years later, he has finished one of them – a giant pin barrel harp – but it's too delicate to sit in a garden.

Dagg says: "It's my fault and no one else's. I severely underestimated the time and effort, as well as the expense it would take. And now that it's finished, it would be a recipe for disaster to leave it outside."

Is this not beautiful? If you define art as something that has no purpose, this is the purest example I have ever seen. There was an attempt to impose function, one single function, on Dagg's pieces – that they would brighten up a garden – but they don't fulfil it. Or rather, it doesn't fulfil it. There were supposed to be three but there is only one. This is rule-breaking, purposeless, perfect art.

It is also a fantastic-looking thing. If I had a spare £27,000 and a giant house with a working, replica sun in the lounge, I would buy it.

There is something wonderful about this being commissioned by the English Folk Dance and Song Society, itself hardly driven by the cold, hard reality of modern market forces. How could a deal struck between that organisation and this artist ever have ended differently?

I imagine a tinkle of bells outside Mr Dagg's workshop, some time in the summer of 2008, as the big cheeses of English Folk jig in to monitor proceedings, waving their handkerchiefs in greeting.

"Are the sculptures ready?"

"No."

"No! Nonny nonny no! See you next year!"

If you had any appreciation for the principle of art, you couldn't possibly mind. This brings me, naturally, to Martin Amis.

The young rapscallion (60) is in trouble again, after calling for euthanasia booths where pensioners can be dispatched "with a martini and a medal". This extreme and evidently unserious solution to what he describes as a "silver tsunami" threatening to flood the domestic coast has been written up in high dudgeon by a disapproving press, studded with furious condemnations from all the obvious places.

They are missing the point entirely, just as they do when they slam Martin Amis for making "misogynistic" or "Islamophobic" statements. He isn't a politician, a religious leader nor even a philosopher. He's an artist. It doesn't matter what he says, as long as he says it beautifully. Which he always does. Never mind the content, feel the form!

I have a certain awestruck reverence for Martin Amis because of what he can do with words. It annoys me to a near-American degree when I see him described sarcastically or disrespectfully by interviewers, news reporters and columnists, who, as writers themselves, could surely be a little humbler at the master's feet.

In the interview where Amis made these remarks, the opening question was some anodyne icebreaker about his grandchild. Still settling into his chair, he replied casually that toddlers are "like little drunks, staggering around the place", yet also "a telegram from a funeral parlour". How can you be cheeky, after that?

One national newspaper, reporting on potential offence taken by the elderly at the booth business, listed previous victims of the Amis drawl before pointing out that "none of these opponents were as tough as his new target promises to be".

Were? Was! None of these opponents WAS as tough! You take the mickey out of this man, who fashions sentences like miniature Taj Mahals in the eyes of needles, when you can't even make a sentence AT ALL? It's like watching an obese man in a sweat-stained shellsuit claim that Jennifer Lopez leaves him cold. That solecism, in that context, made me so angry that it took four smooth, refreshing cups of Café Hag to calm down.

Martin Amis is no Henry Dagg when it comes to worldliness. He has got the hang of big advances, delivery deadlines, press coverage and financial success. But the principle is the same. His speech is an artwork; only the philistine finds fault with its functionality.

You may not actually know that anyone has found fault with Henry Dagg. But he suffered as much controversy as Martin Amis, last week, because the £27,000 sculpture fee came via English Folk Dance from an original lottery grant. There are angry shouts about "our money" going to someone who cannot deliver on time or to purpose.

But isn't that the whole point of arts funding? If Henry Dagg were on top of the time/profit ratio, he wouldn't need support. There are no lottery funds required for Damien Hirst, who employs an army of helpers to knock out his pieces and flog them for millions. Aren't subsidies supposed to facilitate the great dream of art for art's sake, freeing it from the crushing restraints of marketability? Saving us from a world where all art is plastered with breathless mentions of the Fundu Lagoon holiday resort?

When I hear that this grant ended up in the hands of a man who became so obsessed with the making of his works that he spent an accidental three years on one of them, forgot the other two completely, went gradually skint as he pored over a creation that ended up beautiful, unsellable and absolutely pointless, I think: good. For once, a chunk of national money is doing exactly what it is supposed to do.